COLD-ROLLED STEEL PLATE HAVING EXCELLENT QUALITY OF SURFACE AFTER FORMING AND ABILITY FOR STRENGTHENING AT ANNEALING, AS WELL AS METHOD FOR ITS MANUFACTURE Russian patent published in 2014 - IPC C22C38/12 C21D8/04 

FIELD: metallurgy.

SUBSTANCE: plate is made from steel containing the following, wt %: 0.0005-0.0050 C, not more than 0.30 Si, not more than 1.50 Mn, not more than 0.100 P, not more than 0.020 S, and not more than 0.080 Al_sol. (acid-soluble aluminium), not more than 0.0045 N, 0.003-0.100 Nb, and Fe and inevitable impurities are the rest. Content of carbon and niobium in steel meets the ratio of 0.50≤([%Nb]/93)/([%C]/12)≤1.50.

EFFECT: plate has high quality of surface after forming and ability for strengthening at annealing.

5 cl, 2 tbl, 1 ex